1. Fingerprints

2. History of Fingerprints
Fingerprints pressed into clay tablet contracts have been found that date back to BC in Babylon
In ancient China, fingerprints were inked onto all official documents like contacts and loans
The oldest known fingerprinted document is from third century BC China
The oldest known study of fingerprints in Western culture is from 1684

4. In 1788, Johann Christoph Andreas Mayer discovered that no two people have the same fingerprints
Fingerprints were first gathered from criminals in Paris in 1879 by Alphonse Bertillion
Bertillion's system identified a repeat offender in 1883, and was used to solve a murder in 1902
In 1896, Sir Edmund Richard Henry invented the ten card, which is still in use today
The ten card has a place for all ten fingerprints, plus places for all five prints on each hand taken at once

6. Formation of Fingerprints
Fingerprints are a result of the raised ridges on the tips of the fingers
The print that is left behind is made of natural secretions from the sweat glands
Combination of water, oils, salts, and dirt
Fingerprints form in the womb, usually at the beginning of the 10th week of pregnancy
Prints on the palms, soles, and lips also form at this time

7. The fingerprints are made in the basal layer, a special layer in the epidermis where new skin cells are made
In a fetus, the basal layer grows faster than the epidermis on the outside and the dermis on the inside
Because of its fast growth, the basal layer collapses and folds in different directions
The pattern cannot be changed by skin injuries because the epidermis protects it

9. Characteristics of Fingerprints
Fingerprints can be loops, whorls, and arches
65% of the population have loops
30% of the population have whorls
5% of the population have arches

10. Loop
Whorl
Arch

11. The ridges on loops enter the center of the finger from the left or the right side and exit from the same side they enter

12. Whorls look like a bullseye

13. Arches have ridges that enter from one side and exit from the other

14. The core is the center of a loop or a whorl
A triangular region located near a loop is called a delta
Some of the ridge patterns near the delta will rise above the triangular regions, and others will fall below

17. A ridge count can be used in identification as well
In order to take a ridge count, you draw a line from the center of the core to the edge of the delta and count all the ridges that are crossed

18. Types of Whorls
Whorls can be plain (24%), central pocket loop (2%), double loop (4%), or accidental (0.01%)
The plain whorl has one or more ridges that make a complete spiral
It has two deltas
A line between these two deltas will cross at least one of the center ridge lines

21. The central pocket loop whorl has one or more ridges that make a complete circle
It has two deltas as well, but a line drawn between them will not cross any of the center ridge lines

23. The double loop whorl has two separate loop formations and two deltas

25. The accidental whorl has two deltas, and its ridge lines are a combination of two other whorl patterns

27. Types of Arches Arches can be plain (4%) or tented (1%)
In the plain arch, ridges enter from one side, rise in the center, and exit from the other side
There are no angles and no loops

29. The tented arch has all the characteristics of the plain arch, but it does make an angle in the center
A delta may be present towards the center

31. Minutiae
Every individual, including identical twins, has their own unique ridge pattern due to minutiae
Minutiae are very small details in the ridge patterns of fingerprints
Minutiae, along with ridge counts, the differences between ridges, and their locations make up fingerprint identification
There are about 150 individual ridge characteristics on one fingerprint

33. When forensic investigators examine a fingerprint, they are identifying the unique signature of a person
In order to match fingerprints, a minimum number of comparison points are needed

34. Types of Fingerprints
Patent fingerprints are visible prints that are left on a smooth surface
Blood, ink, or some other liquid comes in contact with the hands, and the hands transfer that liquid to the surface
Plastic fingerprints are indentations left in soft materials like clay, putty, or wax
Latent fingerprints are caused by the transfer of oils and other body secretions onto a surface
Latent prints are invisible until they are dusted with powder

36. Can Fingerprints Be Altered or Disguised?
For the most part, no
Fingerprints may be altered, but only by long- term contact with very rough surfaces
John Dillinger tried to alter his fingerprints using acid
Acid does burn off fingerprints, but they always grow back

38. How Reliable Is Fingerprinting as a Means of Identification?
Due to human error and judgment, fingerprint identification is not 100%
In a recent test of fingerprint analysts, it was found that one in five analysts made one false- positive identification
For this reason, results are often checked and double-checked

39. How Are Fingerprints Analyzed?
Before 1999, all fingerprint analysis was done manually
The FBI has developed the Integrated Automated Fingerprint Identification System (IAFIS or AFIS)
IAFIS provides digital, automated fingerprint searches, electronic storage of fingerprint photographs, and electronic exchange of results and files
IAFIS runs 24 hours a day, 365 days a year

40. Law enforcement agencies can now get fingerprint results through IAFIS within 2 hours
Within IAFIS, there is the Criminal Master File, which contains the fingerprints and criminal histories of 47 million people
This is the largest database of its kind in the world
Local and federal law enforcement agencies voluntarily submit information to the Criminal Master File
Local and federal agencies do not, however, pool their data

42. How Are Latent Fingerprints Collected?
Dusting a surface with special powder makes the prints visible
Tape is then used to lift and preserve the fingerprint
The tape is placed on an evidence card that contains the date, time, location, and collector's name
Fingerprints are always photographed before they are lifted

43. Getting a latent print off a surface that is not smooth requires chemicals
When the fingerprint residue combines with these chemicals, the print becomes visible

45. The Future of Fingerprinting
New digital scanning technology is allowing fingerprints to be scanned at the rate of dpi.
This high resolution allows us to see the pore patterns on the ridges.
This leads to better fingerprint matching.
We are also investigating better methods of identifying substances that are transferred to our fingerprints when we touch things.
Ex: gunpowder residue